Researchers follow the noise to find composite images
Photo Issues
Researchers at the University of Albany have developed an efficient and automatic process for identifying composite images, based on the different noise patterns between the two images. In a paper presented at the IEEE's International Conference on Computational Photography, a team led by Siwei Lyu showed they were able to find and locate composited material in images from an online 'Photoshopping' contest site worth1000.com. The team's algorithm exploits the tendency for image noise (regardless of source) to have a characteristic shape (kurtosis). Scanning the image for areas with different noise patterns allows the system to identify non-original content.
Source: News: Digital Photography Review (dpreview.com)